Other than instances where electronic components are each handled as independent components, there are also many instances where a module, in which at least one electronic component is mounted on a circuit board so as to perform a specific function, is handled as one component. In such an electronic module, there are also many instances where the electronic component mounted on the circuit board is entirely sealed with a resin composition, so as to protect the electronic component and to reinforce bonding between the circuit board and the electronic component.
Such a resin composition mainly includes a thermosetting resin such as an epoxy resin or a phenol resin, and is, in a molten state, supplied around the electronic component and into gaps between the electronic component and the circuit board, followed by curing. This causes formation of a solid matter (hereinafter referred to as mold body) which encompasses the electronic component.
The reason why a resin composition including an epoxy resin or a phenol resin is used for formation of the mold body, is because such a resin composition has low viscosity when in a molten state, and can therefore be easily supplied in sufficient amounts into gaps between the electronic component and the circuit board. However, the mold body formed from such a resin composition has a low modulus of elasticity, and there are instances where bonding between the electronic component and the circuit board cannot be reinforced with sufficient strength, against impacts due to drops or the like.
Therefore, a proposal has been made for a reinforcement structure for an electronic module, by which sufficient reinforcement strength can be obtained by disposing a reinforcement frame around an electronic component mounted on a circuit board, and then filling a resin composition into the frame to form a mold body (c.f., PTL 1).